Ventilation interfaces requiring a cushion for providing a seal with a user's face are used for various applications. One such application involves current treatments for obstructive sleep apnea syndrome.
Obstructive sleep apnea syndrome (commonly referred to as obstructive sleep apnea, sleep apnea syndrome, and/or sleep apnea) is a medical condition that includes repeated, prolonged episodes of cessation of breathing during sleep. During a period of wakefulness, the muscles of the upper part of the throat passage of an individual keep the passage open, thereby permitting an adequate amount of oxygen to flow into the lungs. During sleep, the throat passage tends to narrow due to the relaxation of the muscles. In those individuals having a relatively normal-sized throat passage, the narrowed throat passage remains open enough to permit an adequate amount of oxygen to flow into the lungs. However, in those individuals having a relatively smaller-sized throat passage, the narrowed throat passage prohibits an adequate amount of oxygen from flowing into the lungs. Additionally, a nasal obstruction, such as a relatively large tongue, and/or certain shapes of the palate and/or the jaw of the individual, further prohibit an adequate amount of oxygen from flowing into the lungs.
An individual having the above-discussed conditions can stop breathing for one or more prolonged periods of time (e.g., ten seconds or more). The prolonged periods of time during which breathing is stopped, or apneas, are generally followed by sudden reflexive attempts to breathe. The reflexive attempts to breathe are generally accompanied by a change from a relatively deeper stage of sleep to a relatively lighter stage of sleep. As a result, the individual suffering from obstructive sleep apnea syndrome generally experiences fragmented sleep that is not restful. The fragmented sleep results in one or more of excessive and/or inappropriate daytime drowsiness, headache, weight gain or loss, limited attention span, memory loss, poor judgment, personality changes, lethargy, inability to maintain concentration, and depression.
Other medical conditions can also prevent individuals, including adults and infants, from receiving an adequate amount of oxygen into the lungs. For example, an infant who is born prematurely can have lungs that are not developed to an extent necessary to receive an adequate amount of oxygen. Further, prior to, during and/or subsequent to certain medical procedures and/or medical treatments, an individual can be unable to receive an adequate amount of oxygen.
Under these circumstances, it is known to use a ventilation interface to apply a positive pressure to the throat of the individual, thereby permitting an adequate amount of oxygen to flow into the lungs. In known ventilation interfaces, oxygen and/or room air containing oxygen is delivered through the mouth and/or nose of the individual.
Existing types of positive pressure applied by the known ventilation interface include continuous positive airway pressure (CPAP), in which a positive pressure is maintained in the throat passage throughout a respiratory cycle, bi-level positive airway pressure (BiPAP), in which a relatively high positive pressure is maintained during inspiration and a relatively low positive pressure is maintained during expiration, and intermittent mechanical positive pressure ventilation (IPPV) in which a positive pressure is applied when apnea is sensed (I.e., the positive airway pressure is applied intermittently or non-continuously)
Ventilation interfaces of ventilation systems include nasal masks and full masks, among others. For example, many nasal ventilation systems include a mask interface that fits over the nose of a user. The mask is intended to provide a space of gas (e.g., air) for inhalation into the lungs for respiration. Such systems frequently suffer from gas leakage, creating an inability to assure ventilation in many users.
For example, some conventional masks incorporate a sealing surface that extends around the periphery of the mask. The sealing surface is often a molded or formed surface made from a resilient material including elastomers such as plastics, rubbers and foams. Such masks have performed well when the fit is good between the contoured sealing surface and the corresponding contours of the user's face.
Nevertheless, some users will not have an optimal seal fit and gaps in the seal-to-face interface do occur. Often this is remedied by applying greater force to further compress the sealing surface against a user's face, thereby attaining a seal in those areas where the gaps occurred. This often produces user discomfort and may produce various types of skin irritation, particularly where the applied force exceeds the local perfusion pressure (i.e. the pressure that is sufficient to cut off surface blood flow).
Also, because many conventional ventilation systems use a headgear system having straps to bind the mask in place; the system is tightened to obtain a sufficient seal if one does not exist. The mask, headgear and/or individual straps thereby place greater pressure on the patient's face and/or head. Thus, discomfort to a patient can occur at places remote from the sealing surface.
Sealing problems causing discomfort are often exacerbated when the positive pressure of the gas being supplied is relatively high or is cyclical to high levels. The mask must be held against the face with a force sufficient to seal against leakage of the peak pressure of the supplied gas and as the gas pressure increases so does the needed force to prevent leakage.
Overall, user discomfort must be taken into consideration as it may well cause discontinued cooperation with the treatment regimen.
Various cushions for ventilation mask are known. For example, numerous patents teach nasal cushions for nasal masks, such as related U.S. Pat. No. 6,112,746 (Kwok et al.), U.S. Pat. No. 6,357,441 (Kwok et al.) and U.S. Pat. No. 6,634,358 (Kwok et al.), assigned to ResMed, Inc., the disclosures of which are hereby incorporated by reference in their entireties.